This review reports the progress on the recent development of micromixers. The review first presents the different micromixer types and designs. Micromixers in this review are categorized as passive micromixers and active micromixers. Due to the simple fabrication technology and the easy implementation in a complex microfluidic system, passive micromixers will be the focus of this review. Next, the review discusses the operation points of the micromixers based on characteristic dimensionless numbers such as Reynolds number Re, Peclet number Pe, and in dynamic cases the Strouhal number St. The fabrication technologies for different mixer types are also analysed. Quantification techniques for evaluation of the performance of micromixers are discussed. Finally, the review addresses typical applications of micromixers.

A highly soft, stretchable, and sticky polydimethylsiloxane-based elastomer is achieved by adding small fractions of an amine-based polymer. The modified elastomer is tuned with a simple mixing step and shows good processability for microstructure fabrication. The modified elastomer shows excellent compatibility with an epidermal strain sensor on human skin.

Highly sensitive flexible tactile sensors that can be fabricated in a low cost and efficient way are in great demand for intelligent soft robotics and friendly human–machine interaction. Herein, a highly sensitive flexible tactile sensor is developed by using bionic micropatterned polydimethylsiloxane (m‐PDMS) replicated from lotus leaf. The m‐PDMS substrate consists of high‐aspect‐ratio and low‐density microtowers, and is covered by ultrathin silver nanowires as a bottom electrode. The capacitive sensing device is constructed by sandwiching the bottom electrode, a colorless polyimides dielectric layer, and a top electrode, and exhibits a high sensitivity of ≈1.2 k Pa−1, a ultralow limit of detection <0.8 Pa, and a fast response time of 36 ms. The finite‐elemental analysis indicates that the sparse and high‐aspect‐ratio microtowers are critical to achieve high sensitivity, low limit of detection, and fast response to external stimulus. The flexible tactile sensor also exhibits high robustness: it can be tested for at least 100 000 cycles without showing fatigue. More importantly, the flexible tactile sensors are potentially useful in intelligent soft robots, health monitoring, and motion detection. Besides, the fabrication strategy may offer a guideline to design other microstructures for improving the performance of flexible tactile sensors.

Flexible electronic skins (e-skins) with high sensitivity and broad-range pressure sensing are highly desired in artificial intelligence, and humanmachine interaction. Capacitive-type e-skins have a simple configuration, but the change in dimensions of the dielectric layer is often quite limited, although introducing surface microstructures might improve the sensitivity in some extent. Moreover, such surface structures typically require costly microfabrication methods to fabricate. Here, a low-cost microstructured ionic gel (MIG) with uniform cone-like surface microstructures for highperformance capacitive e-skins is reported. The MIG film is templated from a Calathea zebrine leaf using soft lithography, and sandwiched by two flexible electrodes. The device exhibits a low limit of detection down to 0.1 Pa, a ultrahigh sensitivity of 54.31 kPa −1 in the low pressure regime (<0.5 kPa), and the sensitivity keeps larger than 1 kPa −1 over a broad-range pressure from 0.1 Pa to 115 kPa. Electric double layers (EDL) form on both the top and bottom interfaces, and the area of EDL of the rough interface increases as the cones are compressed. Such ionic skins with biomimetic gel templated Calathea zebrine leaf allow for sensitive tactile sensing in the applications of human-machine interaction.